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Digenic Junctional Epidermolysis Bullosa: Mutations in COL17A1 and LAMB3 Genes
Michaela Floeth, Leena Bruckner-Tuderman The American Journal of Human Genetics Volume 65, Issue 6, Pages (December 1999) DOI: /302672 Copyright © 1999 The American Society of Human Genetics Terms and Conditions
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Figure 1 Phenotype of the proband. The clinical phenotype included features of both the GABEB and JEB Herlitz subtypes. A, Proband seen, at the age of 7 mo, with generalized skin blistering but with minimal involvement of the mucous membranes and with normal body height and weight. B, Paronychia-like affection of the fingers, as typically seen in JEB Herlitz. The American Journal of Human Genetics , DOI: ( /302672) Copyright © 1999 The American Society of Human Genetics Terms and Conditions
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Figure 2 Pedigree and LAMB3 and COL17A1 mutations. A, Pedigree demonstrating recessive inheritance of the mutations. Areas with horizontal stripes indicate paternal COL17A1 mutations; dotted areas, maternal COL17A1 mutations; blackened areas, maternal LAMB3 mutations. B, Paternal COL17A1 mutation, which was novel—a heterozygous 2669 T→G transversion in exon 37—and was designated “L855X.” Verification of the mutation by AspI digestion demonstrated that the father and the paternal grandmother were heterozygous for this mutation. C, Maternal COL17A1 mutation, which was a heterozygous 3781C→T transition in exon 51 and was designated “R1226X” (McGrath et al. 1995; Jonkman et al. 1997; Schumann et al. 1997). The mutation was also found, by TaqI digestion, in the mother's and both the half-sisters' DNA, but it was not found in a control or in the father. D, LAMB3 mutation R635X (Kivirikko et al. 1996), which was verified by both BglII digestion of the PCR amplification products of exon 14 and by dideoxynucleotide sequencing (not shown). In addition to the proband, the mother was heterozygous for this mutation. In B–D, the numbers above the agarose-gel images denote the individuals in the pedigree, and “C” denotes the control. The American Journal of Human Genetics , DOI: ( /302672) Copyright © 1999 The American Society of Human Genetics Terms and Conditions
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Figure 3 Northern blotting of collagen XVII and laminin 5 mRNA. A strong signal of the 6-kb collagen XVII mRNA was detected in control keratinocytes (left panel). In contrast, collagen XVII mRNA that was isolated from the JEB patient's keratinocytes (left panel) produced a negative signal, suggesting nonsense-mediated mRNA decay in these cells. The blot was intentionally overexposed to reveal potentially small amounts of mRNA in the patient's cells. When laminin 5 cDNA was used for hybridization, a strong 3.5-kb laminin 5 mRNA band was seen in normal keratinocytes (right panel). The keratinocytes of the patient with JEB produced a clearly weaker band (right panel). GAPDH cDNA was used as a reference probe to correct for minor differences in RNA loading. Densitometric analysis of the laminin 5 signals indicated that the patient's cells contained ∼55% of the laminin 5 mRNA seen in controls. C = control; Pat = patient. The American Journal of Human Genetics , DOI: ( /302672) Copyright © 1999 The American Society of Human Genetics Terms and Conditions
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Figure 4 Collagen XVII and laminin 5 protein expression in situ. Indirect immunofluorescence staining of control (A and B) and JEB (C and D) skin biopsy specimens, with antibodies to collagen XVII (A and C) and laminin 5 (B and D). In normal skin, both collagen XVII (A) and laminin 5 (B) antibodies showed a linear fluorescence at the dermal-epidermal junction. In the proband's skin, collagen XVII was absent (C), and the laminin 5 staining was attenuated (D). The American Journal of Human Genetics , DOI: ( /302672) Copyright © 1999 The American Society of Human Genetics Terms and Conditions
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